ATTRACTIVE EDGE-TO-FACE AROMATIC INTERACTIONS IN A RANGE OF SIMPLE NITRONES, OXAZIRIDINES AND IMINES. By J.F. Malone^a, D.R. Boyd^a, T.A. Evans^a and A. Smith^a, W.B. Jennings^b and W. O'Sullivan^b, School of Chemistry^a, The Queen's University of Belfast, Belfast, N. Ireland and Department of Chemistry^b, University College, Cork, Republic of Ireland.

Attractive intramolecular edge-to-face type interactions between aromatic moieties have been identified by X-Ray studies and NMR in a range of simple nitrones, oxaziridines and imines. Intramolecular hydrogen to mid-aromatic ring distances of 2.60Å, 2.66Å, 2.70Å, 2.73Å and 2.78Å are observed. The Hunter-Sanders rules (C.A. Hunter and J.K. Sanders, J. Am. Chem. Soc., 1990, 112, 5525) are applied to the interactions and are found to be in agreement with the observations. Analysis of the crystal lattices have shown similar intermolecular interactions affecting the crystal packing, in some cases quite significantly. One case showed evidence in the NMR for an intramolecular edge-to-face type interaction which was not observed in the solid state where several intermolecular aromatic-aromatic interactions seemed to be controlling the geometry. The [[sigma]] polarization of the atoms in the rings is proposed as being of importance in determining the type of interaction observed and hence the geometry.